The present invention relates generally to computerized systems and more particularly to connecting/interfacing hard disk drives having standard ATA interfaces to microprocessors (or other such devices/systems) which have generic memory interfaces, but which do not implement all the features/requirements of the ATA interface.
The need to interface ATA hard disk drives (as well as other types of peripherals) with non-ATA type computerized systems comes about from the continuing trend to integrate miniature hard disk drives into a wider variety of portable consumer electronic devices where, traditionally, hard disks have not been used and where there is no standard hard disk interface (such as ATA) available. It would therefore be an advantage to be able to connect a hard disk drive to existing generic external bus interfaces (such as an external memory bus) on microprocessors commonly used in portable consumer electronic devices such as cell phones, MP3 players, digital video recorders, PDAs, etc. The advantage comes from being able to create new products with hard disk storage quickly, minimizing costs by not requiring a separate interface with additional pins, and eliminating the need to go out and design new ICs, etc.
Keep in mind that there are microprocessors and other such computerized systems that do, indeed, include ATA interfaces, as exemplified by system 7 shown in FIG. 1. As seen there, a host 8 is shown including its own ATA interface 9. For purposes of simplicity, the term “host” is used to denote any device which the disk drive (or other such peripheral) is connected to via some type of interface such that the device and the peripheral cooperate with one another in the manner described herein. As indicated above, the host could be, for example, a microprocessor as part of a computer or other such computerized system. Given the host 8 includes an ATA interface 9, no problems arise in connecting an ATA type device, for example disk drive 10, to the host 8 via the ATA interface 9, at least as far as the present disclosure is concerned, as will be discussed hereinafter. For completeness, System 7 is shown including a non-ATA interface, specifically an external memory interface 11, for other memory devices and other such peripherals 12.
As will be described in more detail hereinafter, the problem arises where the particular peripheral being interfaced with the host has an ATA interface, for example, ATA disk drive 10, but where the host itself does not have its own ATA interface to support the connection. In this case, it is often possible to connect the ATA disk drive to a different interface on the host, such as an external memory interface on the host as shown in FIG. 2, however this type of connection has up until now required that the external memory interface 26 have available all of the signals required by the ATA Interface 30 on ATA disk drive 28. As an example, consider the standard ATA interface in disk drive 10, which interface contains a signal called IORDY (Input/Output Ready). This signal is either asserted or de-asserted. When data transfers are occurring between such a disk drive and a host having a cooperating ATA interface, as in FIG. 1, the host is able to recognize and act on the asserted or de-asserted IORDY signal without any problem. For example, if host 8 executes a read or write cycle to disk drive 10 and the disk drive is able to complete the request within the time cycles allotted, the IORDY signal from the disk drive to the host will be in its asserted state and remain so throughout the requested task. On the other hand, if because of internal conditions, the disk drive cannot service the read or write access cycle on the ATA interface bus within the allotted or usual cycle time, the disk drive causes the IORDY signal to be switched to its de-asserted state which, in essence, means that the disk drive is asking the host to dynamically extend the bus cycle time in order for the disk drive to carry out the particular operation in question. In the case where the host includes a cooperating ATA interface, as in the case of host 8, this is not a problem. The host will respond by providing the necessary dynamic extension. On the other hand, where the host does not have a cooperating ATA interface, and the disk drive must be connected to an interface bus which has no signal equivalent to IORDY available, no extension will be made available and the probable result is that the task in question will not be completed correctly and some data will be lost or corrupted. That, of course, is a problem which is considered to be resolved, in conjunction with providing still further advantages.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.